As defined by Perry's Chemical Engineers' Handbook, 7th edition, liquid extraction is a process for separating components in solution by their distribution between two immiscible phases. Such a process is also referred to as Solvent Extraction, but Solvent Extraction also implies the leaching of a soluble substance from a solid.
The present invention relates to a program of events and ingredients that make it possible to produce a non-aqueous laundering machine that is self contained, automatic and relatively compact that can be used in the home as well as commercially. The machine would offer the consumer the ability not only to launder their traditional fabrics (cotton, polyesters, etc.) at home, but also have the ability to handle delicate fabrics such as dry-clean only fabrics as well. There have been numerous attempts at making a non-aqueous laundering system; however, there have been many limitations associated with such attempts.
Traditional dry-cleaning solvents such as perchloroethylene are not feasible for in-home applications because they suffer from the disadvantage of having perceived environmental and health risks. Fluorinated solvents such as hydrofluoroethers have been posed as potential solvents for such an application. These solvents are environmentally friendly and have high vapor pressures leading to fast drying times, but these solvents don't currently provide the cleaning needed in such a system.
Other solvents have been listed as potential fluids for such an application. Siloxane-based materials, glycol ethers and hydrocarbon-based solvents all have been investigated. Typically, these solvents are combustible fluids but the art teaches some level of soil removal. However, since these solvents are combustible and usually have low vapor pressures, it would be difficult to dry with traditional convection heating systems. The solvents have low vapor pressures making evaporation slow thus increasing the drying time needed for such systems. Currently, the National Fire Protection Association has product codes associated for flammable solvents. These safety codes limit the potential heat such solvents could see or the infrastructure needed to operate the machine. In traditional washer/dryer combination machines, the capacity or load size is limited based on the drying rate. However, with the present invention, the capacity of the machines will be more dependent upon the size of the drum than the size of the load.
The present invention uses some of these aforementioned solvents to clean fabrics without the drying problems associated with these solvents. This is accomplished by using a select rinse fluid that solves many of these drying problems.
U.S. Pat. No. 5,498,266 describes a method using petroleum-based solvent vapors wherein perfluorocarbon vapors are admixed with petroleum solvent vapors to remove the solvents from the fabrics and provide improvements in safety by reducing the likelihood of ignition or explosion of the vapors. However, the long-term stability of these mixtures is unknown but has the potential of separating due to dissociating the separate components.
U.S. Pat. No. 6,045,588 describes a method for washing, drying and recovering using an inert working fluid. Additionally, this application teaches the use of liquid extraction with an inert working fluid along with washing and drying. This new patent application differs from U.S. Pat. No. 6,045,588 in that it describes preferred embodiments to minimize the amount of rinse fluid needed as well as recovery methods, apparatuses and sequences not previously described.
U.S. Pat. No. 6,558,432 describes the use of a pressurized fluid solvent such as carbon dioxide to avoid the drying issues. In accordance with these methods, pressures of about 500 to 1000 psi are required. These conditions would result in larger machines than need be for such an operation. Additionally, this is an immersion process that may require more than one rinse so additional storage capacity is needed.
US20030084588 describes the use of a high vapor pressure, above 3-mm Hg, co-solvent that is subjected to lipophilic fluid containing fabric articles. While a high vapor pressure solvent may be preferred in such a system, US20030084588 fails to disclose potential methods of applying the fluid, when the fluid should be used and methods minimizing the amount of fluid needed. Finally, this patent fails to identify potential recovery strategies for the high vapor pressure co-solvent.
Various perfluorocarbons materials have been employed alone or in combination with cleaning additives for washing printed circuit boards and other electrical substrates, as described for example in U.S. Pat. No. 5,503,681. Spray cleaning of rigid substrates is very different from laundering soft fabric loads. Moreover, cleaning of electrical substrates is performed in high technology manufacturing facilities employing a multi-stage that is not readily adaptable to such a cleaning application.
The first object of the present invention is to devise a complete sequence of non-aqueous laundering operations using a combination of materials that can be economically separated and used over and over again in a self contained non-aqueous laundering machine.
It is a further object of the invention to describe specific processes for introducing the select rinse fluid.
It is an object of the invention to describe techniques and methods for minimizing the amount of select rinse fluid needed and the time that the select rinse fluid should be in contact with the working fluid and fabric articles.
It is a further object of the invention to describe a low temperature drying process that would result in improved fabric care and lower energy requirements for such a non-aqueous laundering machine.
It is still another object of the invention to disclose the advantage of increasing the size of the load to be dried without significantly increasing the drying time as is common with traditional aqueous-based machines and non-aqueous machines using some of these methods.
It is another object of the invention to describe recovery methods and techniques not only for the select rinse fluid, but also additionally for the working fluid and wash liquor.
It is a further object of the invention to describe apparatuses designed to complete the select rinse fluid application, low temperature drying and recovery methods.
It is a further object of the invention that the soils removed are concentrated and disposed of in an environmentally friendly manner.
It is a further object that the materials used are all of a type that avoids explosion and manages flammability hazards.
Further objects and advantages of the invention will become apparent to those skilled in the art to which this invention relates from the following description of the drawings and preferred embodiments that follow: